He’s ruthless. He’s secretive. He’s worth $30 billion. He’s been accused of being tighter with his wealth than a lemonade stand—so much so that we recently named him one of the "six least generous" leaders in tech. But is all that about to change? Is Amazon CEO Jeff Bezos ready to begin thawing his stoic stance on personal philanthropy?

It would be nice, wouldn’t it? Looking around at the respective philanthropic portfolios of Bezos’ billionaire peers in tech—Bill Gates, Pierre Omidyar, Mark Zuckerberg—makes it easy to imagine what the good Bezos could accomplish if he just loosened his purse strings a bit. In the past few years, Bezos has periodically broken his stony, cold façade to dispense a few million here or there. In 2009, Bezos gave the Fred Hutchinson Cancer Research Center a $10 million challenge gift to expand the use of immunotherapy for breast, ovarian, and prostate cancers. In 2011, he and his wife, MacKenzie, gave $15 million for the study of neurological disorders at Princeton. (See IP's profile of Bezos.)

Now comes the biggest Bezos gift yet: $20 million to expand the previously funded immunotherapy at the Hutchinson Center to take on lung, ovarian, pancreatic, and colon cancers.

This is exactly the sort of project Bezos and MacKenzie seem to favor—at least in their nascent phase of giving. Bezos, not surprisingly, is a huge tech guy, someone who thrills at the potential of technology to solve the world’s problems. And it really doesn’t get a whole lot more remarkable than rigging a way to reprogram a body’s immune system to take down its own cancer, does it? That’s the heart of this immunotherapy initiative, and Hutchinson is moving forward in leaps and bounds, thanks in no small part to the Bezoses’ money. (Less is know about MacKenzie's passions. See our profile here.)

It’s clear that the couple is developing a relationship with Hutch, and we should all be expecting future gifts headed in this direction. But when? For what? And most importantly, why is it taking Bezos so long to motivate his giving? It’s tempting to speculate that he may just be in a protracted ramping-up stage, as Bill Gates once was prior to embarking on his own philanthropic path in 1994. The Bezos Family Foundation—managed by Bezos’ mother and stepfather—is funded by a chunk of early Amazon stock much the same way Bill Gates dad’s foundation was in Microsoft’s early days. As Gates the younger found his footing, he gradually subsumed his dad’s foundation, rolling all the Gates family giving into one giant, supergenerous entity.